The fall of an empire does not always begin with a foreign invasion; often, it starts with a devastating internal collapse. God will bring ruin upon Egypt not through an outside army, but by sparking a fierce civil war and completely dismantling their social solidarity. This internal fracturing will leave them too weak to unite against external enemies, rapidly accelerating their downfall [רד״ק, אברבנאל]. The primary approach among commentators is that God will sow deep confusion, provocation, and conflict among the Egyptian people [אבן עזרא, רד״ק, מצודות]. As [רש״י] notes, this divine intervention will quickly manifest as citizens turning violently against one another. Offering a slightly different perspective, [מלבי״ם] suggests that God will essentially use the Egyptians themselves as weapons, turning the population into an internal army that lays siege to its own country.
The progression of this conflict represents an extreme and unnatural breakdown of society. During a typical war, family members and neighbors naturally band together to fight a common enemy, with battles taking place between distant cities or foreign nations. However, in this divine judgment, the natural order is entirely reversed. The violence will ignite within the closest and most unlikely of circles, starting with brother fighting against brother. From the family unit, the hostility will spill outward, turning friend against friend. It will then escalate into a broader civil war of city against city, ultimately reaching the massive scale of one kingdom fighting against another [מלבי״ם, חומת אנך].
The idea of entire kingdoms battling within Egypt raises a natural question, as Egypt was fundamentally a single nation. The commentators explain that the country was historically divided into many distinct regions, districts, or provinces. According to [שד״ל], there were thirty-six such districts. Each area was governed by local ministers or rulers who were ultimately subject to the greater king, much like the regional kings of Canaan. Driven by this divinely inspired conflict, these various districts will turn their weapons on each other, entirely fracturing the state and destroying the Egyptian empire from the inside out [רד״ק, מצודת דוד, אברבנאל].